Electrical energy storage cells are widely used to provide power to electronic, electromechanical, electrochemical, and other useful devices. An electric double layer ultracapacitor, for instance, generally employs a pair of polarizable electrodes that contain carbon particles (e.g., activated carbon) impregnated with a liquid electrolyte. Due to the effective surface area of the particles and the small spacing between the electrodes, large capacitance values may be achieved. Nevertheless, problems remain. For instance, many conventional ultracapacitors are provided in a rigid metal container. These containers are generally bulky and necessitate the use of prefabricated mounting points within the circuit or apparatus, which makes it difficult to accommodate ultracapacitors of different dimensions. While ultracapacitors have also been developed that employ a flexible housing, they tend to still be relatively bulky and have a relatively low capacitance and high equivalent series resistance (“ESR”). As such, a need currently exists for an improved ultracapacitor.